A widespread problem of varactors is that of obtaining a good tunability with regard to the dielectricity.
Varactors are voltage-tunable capacitors in which the capacitance is dependent on a voltage applied thereto, or the capacitance can be altered by a change in the applied voltage. Varactors are employed for example in radiofrequency circuits in which electrical tuning takes place, such as, for example, in filters or phase shifters. Varactors can be used as frequency filters, for example, for radio and radio frequencies which can be electrically tuned. Semiconductor diode varactors have only a low quality factor, a low loading capacity and a limited capacitance range. By contrast, a ferroelectric varactor, in which the capacitance is tuned for example by varying the dielectric constant of a ferroelectric material by means of changing the bias voltage, has a high quality factor, a high loading capacity and at the same time a large capacitance range.